The invention relates to self cooling and self heating containers, and in particular to self-heating and self heating sorption containers which operate without valves which perforate the surfaces of the device. Previous inventions relating to sorption self cooling and self heating containers have been described by the present author in U.S. Pat. Nos. 4,250,720, 4,736,599, 4,928,495, 5,079,932 and 5,168,708. Essentially, the self cooling and self heating containers consists of a chamber containing water, the boiling point of which has been lowered by an air vacuum in the chamber. The chamber communicates through a pipe with another chamber containing a desiccant. As the water boils it cools itself and absorbs heat from a food or a beverage which is preferred to be consumed at low temperatures. The vapor generated by the low boiling point water is removed by the desiccant. The vapor sorbed by the desiccant heats the desiccant. The desiccant then delivers heat to a food or a beverage which is preferred to be consumed at high temperatures. By closing the communication between the water and desiccant chambers the self cooling and self heating device can be stored indefinitely without losing its temperature changing potential. The cooling or heating action is initiated by opening of the communication between the water and the desiccant chambers. Thus, a reversible closing of the communication between the water and the desiccant chamber is essential for the storage and operation of the device. This has been previously achieved by valve means which open and close the pipe between the chambers.
The air vacuum which is required to lower the boiling point of the water, must often be maintained through out months or even years of the shelf life of the food or beverage. To prevent an air leak into the system through the valve an air tight and leak proof valve is essential. Standard valves which are manipulated through means which have perforated the wall of the temperature changer present a continuous leak hazard and are not suited for such strict and long term vacuum requirements. Commercially available vacuum valves are too expensive for use in commonly used beverage containers. In U.S. Pat. No. 5,168,708 I have described a pliable outside surface, such as a bellows, as means to open and close the communication between the water and desiccant chambers without perforating the surfaces of the chambers. In recent U.S. patent applications I have described magnetic means to open and close the communication between the chambers while maintaining the integrity of the chambers surfaces. The magnetic force between two bodies varies inversely as the square of distance between the bodies. The magnetic force is therefore largely decreased with even relatively small distances between a magnet and a magnet responsive object. In recent U.S. patent applications I have described magnet responsive stoppers present inside an air evacuated containers responding to a magnet on the outside surface of the container. A disadvantage of magnetic stopper mechanism is the fact that the stopper must travel a relatively long distance towards and away from the outside magnet in order to close and open the communication between the chambers. The main objective of the present invention is to provide a self cooling container with a closing and opening mechanism which would minimize the distance of travel between the magnet and its magnet responsive object.
An additional disadvantage of a stopper mechanism is the fact the stopper must be fitted tightly into its opening to provide a leak proof seal. This requires a relatively large force not only to push the stopper into its opening but also to pull the stopper from its opening. This force often exceeds the magnetic forces provided by small low cost magnets. Another objective is to provide a magnet responsive closing and opening mechanism which require relatively little force to effectively open and close.